Hydrocarbon processing using fullerene catalysts

ABSTRACT

A process is described for carrying out the dehydrogenation or hydrogenation, including hydrogenolysis, of a hydrocarbon in the presence of one or more soluble fullerene catalysts which have been dissolved in the hydrocarbon (when the hydrocarbon is a liquid capable of dissolving the fullerene catalyst) or dissolved in a solvent which is also a solvent for the hydrocarbon (when the hydrocarbon either is not a liquid or is not a liquid which is a solvent for the fullerene catalyst). The use of a liquid catalyst, i.e., a dissolved fullerene catalyst, inhibits coking reactions to thereby inhibit formation of coke on a solid catalyst or catalyst support by elimination of nucleation points or growth regions for such coke formation.

This is a divisional of application Ser. No. 08/025,502, filed on Mar.3, 1993, now U.S. Pat. No. 5,336,828.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to hydrocarbon processing using fullerenecatalysts. More particularly this invention relates to the use offullerene catalysts for dehydrogenation and hydrogenation, includinghydrogenolysis (cleavage), of hydrocarbons.

2. Description of the Related Art

Conventional dehydrogenation and hydrogenation reactions withhydrocarbons, including the hydrogenolysis or cleavage of the bondbetween an alkyl or substituted alkyl group and an aryl group, haveinvolved the use of solid catalysts, such as metal or metal sulfidecatalysts, e.g., platinum, nickel, molybdenum, etc., usually formed andcarried on a solid support material such as alumina.

However, during such dehydrogenation or hydrogenation reactions, thereis a tendency for a coking reaction to also occur when such catalystsare used, with the coke forming on the metal catalyst and/or catalystsupport. Apparently such a coking reaction occurs, during the course ofthe reaction, due to the presence of the solid catalyst/catalyst supportmaterials which can provide catalytic sites, nucleation points, and aquiescent boundary layer for coke formation by the hydrocarbonreactants. It would, therefore, be preferable to provide a catalyst forsuch reactions which would be: (a) soluble in the hydrocarbonreactant(s) (when the hydrocarbon is a liquid); or (b) soluble in asolvent in which the hydrocarbon reactant(s) will also dissolve or bedispersible (when the hydrocarbon reactant is not liquid); or (c)soluble in a solvent which will be miscible with the hydrocarbonreactant(s) (when the hydrocarbon reactant is a liquid); or (d) solublein a solvent which is miscible with a solvent in which the hydrocarbonreactant(s) is dissolved (when the hydrocarbon reactant is a solid).

Such a catalyst, if soluble, would, of course, not need a solid catalystsupport, and the absence of both the solid catalyst and the solidcatalyst support would eliminate the prior art nucleation source/growthsite for coking, or other undesirable side reactions, resulting inhigher yields and less contamination of either the reactor or theproduct.

SUMMARY OF THE INVENTION

It is, therefore, an object of this invention to provide a new methodfor processing one or more hydrocarbons using a fullerene catalyst forthe dehydrogenation or hydrogenation, including hydrogenolysis, ofhydrocarbons.

It is another object of this invention to provide a new method forprocessing one or more hydrocarbons using a soluble fullerene catalystwhich will eliminate the need for either a solid catalyst or a solidcatalyst support for the dehydrogenation or catalyst support for thedehydrogenation or hydrogenation, including hydrogenolysis, ofhydrocarbons.

These and other objects of the invention will be apparent from thefollowing description of the process of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowsheet illustrating a cleavage or hydrogenolysis reactioncarried out by the method of the invention.

FIG. 2 is a flowsheet illustrating a hydrogenation reaction carried outby the method of the invention.

FIG. 3 is a flowsheet illustrating a dehydrogenation reaction carriedout by the method of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The invention comprises a method for carrying out dehydrogenation(removal of hydrogen) and hydrogenation (addition of hydrogen)reactions, including hydrogenolysis reactions (addition of hydrogeninvolving cleavage) using one or more fullerenes as catalysts. In apreferred embodiment the fullerene catalyst is soluble in the reactantsor the solvent in which the reactants are dissolved so that a source ofnucleation source/growth sites for coking or other undesirable sidereactions is eliminated. However, the use of solid fullerene catalystsfor such reactions should be deemed to be within the scope of theinvention. This could include, for example, a soluble fullerene catalystimmobilized on a solid support; a solid fullerene catalyst; a solidmixture of fullerenes and soot produced, for example, during formationof the fullerenes by evaporation of graphite electrodes; or even, insome instances, the soot itself from a process for producing fullerenes.

The method comprises carrying out the dehydrogenation/hydrogenation(including hydrogenolysis) of one or more hydrocarbons in the presenceof one or more fullerene catalysts. Preferably the fullerene catalyst is(a) soluble in the hydrocarbon reactant(s) (when the hydrocarbon is aliquid); or (b) soluble in a solvent in which the hydrocarbonreactant(s) will also dissolve or be dispersible (when the hydrocarbonreactant is not liquid); or (c) soluble in a solvent which will bemiscible with the hydrocarbon reactant(s) (when the hydrocarbon reactantis a liquid); or (d) soluble in a solvent which is miscible with asolvent in which the hydrocarbon reactant(s) is dissolved (when thehydrocarbon reactant is a solid).

a. The Fullerene Catalyst

The one or more fullerene catalysts useful in the practice of theinvention may be further defined as a three dimensional carbon moleculewhich comprises a clustered carbon structure, generally spherical orspheroidal in shape and having a carbon content generally ranging fromabout 50 to about 90 carbons, although larger carbon content fullerenesare also known to exist and may be useful in the practice of theinvention. These fullerene catalysts are also distinguishable from othercarbon forms such as graphite, diamond, or carbon black in that suchfullerene catalysts are dissolvable in hydrocarbon solvents such as, forexample, toluene and benzene; and they evaporate at much lowertemperatures, i.e. <1000° C., than do conventional forms of carbon,e.g., graphite, which sublimes at over 3600° C. at ambient pressure.

Such fullerene compounds, as shown in FIG. 1, are known to exist, forexample, as C₆₀, C₇₀, C₇₄, C₇₆, C₇₈, C₈₀, C₈₂, and C₈₄ molecules, withthe subscript signifying the number of carbons in the particularfullerene structure. Other fullerenes known to exist and which may beused in the practice of this invention are C₈₆, C₈₈, and C₉₀, and on upby two carbon atoms, e.g., C₉₂, C₉₄, etc. However, the higher carbonnumber fullerenes are not as easily obtained by present known methods.

Generally, the one or more fullerene catalysts useful in the practice ofthe invention may be referred to as one or a mixture of fullereneshaving the general formula C_(n), where n is an even integer from 50 to120, and preferably from about 60 to about 90.

Formation of these fullerene structures, which are used as catalysts fordehydrogenation and hydrogenation of hydrocarbons practice of theinvention, may be by the formation of soot from graphite electrodesfollowed by evaporation or solvent separation of the fullerenes producedin the soot from the remaining carbon forms therein.

Such formation methods are described, for example, by Kratschmer et al.in "Solid C₆₀ : A New Form of Carbon", published in Nature, Volume 247,pp. 354-357, on 27 Sept. 1990; and by Y. K. Bae et al. in "Production,Characterization, and Deposition of Carbon Clusters" prepared for theSymposium on Clusters and Cluster Assembled Materials Special Session onBuckminsterfullerenes, in Boston, MA on Nov. 29, 1990, and published inThe Proceedings of the 1990 Meeting of the MRS Society.

The fullerene catalysts useful in the practice of the invention may alsobe formed and recovered by the method described in copending applicationSer. No. 07/814,721, entitled PROCESS AND APPARATUS FOR PRODUCING ANDSEPARATING FULLERENES, filed Dec. 24, 1991, and assigned to the assigneeof this invention, the disclosure of which is hereby incorporated byreference.

The exact amount of fullerene catalyst used in thedehydrogenation/hydrogenation reaction with one or more hydrocarbonswill vary with the particular hydrocarbon reactant(s), the amount ofreactant(s), and whether the reaction is to be a batch reaction or acontinuous reaction. Usually, however, the amount of fullerene catalystused will vary from about 1 to about 10 grams of fullerene catalyst per100 grams of hydrocarbon reactant(s).

The one or more soluble fullerene catalysts may be dissolved in thehydrocarbon reactant(s), when the hydrocarbon is a liquid and thefullerene catalyst is soluble therein. When the hydrocarbon reactant isnot a liquid--or is not a solvent for the fullerene catalyst, typicalsolvents which may be used to dissolve the fullerene catalyst includealkanes such as decalins, haloalkanes such as trichloroethane andtetrachloroethane, and miscellaneous solvents such as methylthiopheneand carbon disulfide. The choice of solvent will be governed by thespecific reaction conditions employed to effect the reaction. Obviously,the solvent itself should not be subject to any chemical reaction underthose conditions, or be derivable as part of a recycle stream.

Preferably, such a solvent will also serve as a solvent for thehydrocarbon reactant, when the hydrocarbon reactant is a solid, or atleast be miscible with either the liquid hydrocarbon reactant which isnot a solvent for the one or more fullerene catalysts or with a solventin which the solid hydrocarbon reactant(s) is dissolved.

b. Hydrogenolysis (Cleavage) Reactions

In accordance with one aspect of the invention, the above describedfullerene catalysts are used to catalyze a cleavage of a substitutedaromatic at the bond between the ring itself and the moiety bonded tothe ring. For example, toluene (methyl benzene) can be cleaved intobenzene and methane, using a fullerene catalyst in the presence of asource of hydrogen. The general formula for this type of reaction which,in accordance with the invention, is catalyzed with one or morefullerene catalysts, may be written as follows: ##STR1## where Ar is aradical of a 6-30 carbon aromatic ring compound, including, for example,benzene, naphthalene, anthracene, phenanthrene, 1,2,5,6-dibenzanthrene;and M is an aliphatic radical comprising X, R, OR, SR, and NRR', where Xis a halogen other than fluorine, R is a 1-30 carbon alkyl group, and R'is hydrogen or a 1-30 carbon alkyl group. As will be discussed below,hydrogenation may also occur instead of cleavage. Generally the cleavagereaction will be favored over hydrogenation for multiple ring aromaticcompounds, however. Therefore, Ar, in the above formula, is preferably a10-30 carbon multiple ring aromatic radical. The tendency to removedifferent substituents on the rings will vary with steric and electronicfactors.

The one or more soluble fullerene catalysts are used, in thishydrogenolysis reaction, in an amount which varies from about 1 to 10parts by weight per 100 parts by weight of the one or more hydrocarbonreactants.

The hydrogenolysis reaction is carried out at a temperature which mayvary from about 25° C. to about 500° C. and at a pressure which may varyfrom about 100 Torr to about 50,000 Torr. The reaction, when carried outas a batch reaction, is usually carried out for a time period which mayrange from about 1 minute to about 18 hours. When a continuous reactionis carried out, a portion of the reaction mass may be removedcontinuously from the reactor, the desired cleaved products separatedfrom the remainder of the reaction mass, and the non-cleaved materialrecycled back to the reactor.

c. Hydrogenation/Dehydrogenation Reactions

In accordance with another aspect of the invention, the above describedfullerene catalysts are used to either catalyze the hydrogenation of anaromatic or unsaturated aliphatic (olefinic) hydrocarbon, or thedehydrogenation of a saturated linear, branched, or cycloaliphatic(hydroaromatic) hydrocarbon. Since such reactions are reversible, thepresence or absence of hydrogen and temperature will determine whetherthe hydrogenation or dehydrogenation reaction will predominate.

In its simplest form, the hydrogenation reaction of the invention, usingone or more fullerene catalysts, may be illustrated by the followingequation, using toluene as an example of the aromatic to behydrogenated: ##STR2##

Unsaturated hydrocarbons, both olefinic and aromatic, which may behydrogenated by the process of the invention, include any unsaturated2-100 carbon hydrocarbon. Such unsaturated olefinic or aromatichydrocarbons which may be hydrogenated by the process of the inventioninclude, by way of example, ethene, ethyne, propene, propyne,2-methyl,l-propene, 1-pentene, 2-pentene, 2-methyl,l-butene,2-methyl,2-butene, 2,2-dimethyl,l-propene, benzene, naphthalene,anthracene, and phenanthrene.

The one or more soluble fullerene catalysts are used, in thehydrogenation reaction, in an amount which varies from about 1 to 10parts by weight per 100 parts by weight hydrocarbon reactant. The one ormore fullerene catalysts are dissolved in a solvent, which may comprisethe unsaturated hydrocarbon reactant itself.

Preferably, as also previously discussed, such a solvent will also serveas a solvent for the unsaturated hydrocarbon reactant, when thehydrocarbon reactant is a solid, or at least be miscible with the liquidhydrocarbon reactant, when the liquid hydrocarbon reactant is not asolvent for the one or more fullerene catalysts.

The hydrogenation reaction is preferably carried out at a temperaturewhich may vary from about 25° C. to about 500° C. and at a pressurewhich may vary from about 100 Torr to about 50,000 Torr. Thehydrogenation reaction, when carried out as a batch reaction, is usuallycarried out for a time period which may range from about 1 minute toabout 18 hours. In the absence of a source of hydrogen, thedehydrogenation reaction will prevail, as shown in equation (3)illustrated below, using methylcyclohexane as the starting material:##STR3##

Saturated linear, branched, and cyclic hydrocarbons which may bedehydrogenated by the process of the invention may include any 2-100carbon saturated hydrocarbon. Such saturated linear, branched, andcyclic hydrocarbons which may be dehydrogenated by the process of theinvention include, by way of example, ethane, propane, butane, 2-methylpropane, pentane, 2-methyl butane, 2,2-dimethyl propane, hexane,cyclohexane, methyl cyclohexane, dimethyl cyclohexane, etc.

The one or more soluble fullerene catalysts are used, in thedehydrogenation reaction, in an amount which varies from about 1 to 10parts by weight per 100 parts by weight hydrocarbon reactant. Asdiscussed above, the one or more fullerene catalysts are dissolved in asolvent, which may comprise the saturated hydrocarbon reactant itself.

Preferably, as also previously discussed, such a solvent will also serveas a solvent for the hydrocarbon reactant, when the saturatedhydrocarbon reactant is a solid, or at least be miscible with the liquidhydrocarbon reactant, when the liquid hydrocarbon reactant is not asolvent for the one or more fullerene catalysts.

The dehydrogenation reaction is preferably also carried out at atemperature which may vary from about 25° C. to about 500° C. and at apressure which may vary from about 1 Torr to about 1500 Torr. Thedehydrogenation reaction, when carried out as a batch reaction, isusually carried out for a time period which may range from about minuteto about 18 hours.

When a continuous hydrogenation or dehydrogenation reaction is carriedout, a portion of the reaction mass may be removed continuously from thereactor, the desired product is separated from the remainder of thereaction mass, and the remaining material is recycled back to thereactor. In addition, for a hydrogenation reaction, a source of hydrogenis continuously added to the reactor to drive the reaction towardhydrogenation, while for a dehydrogenation reaction, hydrogen gas mustbe continuously removed from the reactor as it is generated to continueto drive the reaction toward dehydrogenation.

Thus, for a continuous hydrogenation process, a source of hydrogen and asource of an unsaturated hydrocarbon, i.e., either an aromatic or anunsaturated aliphatic hydrocarbon, are continuously added to thereactor, while product is continuously removed, separated into thedesired hydrogenated product and unhydrogenated (unsaturated)hydrocarbon, and the unsaturated hydrocarbons are recycled back to thereactor.

Conversely, for a continuous dehydrogenation process, a source of asaturated hydrocarbon, i.e., either a saturated cyclohydrocarbon or analiphatic hydrocarbon, is continuously added to the reactor, hydrogengas, as it is generated, is constantly removed from the reactor, andproduct is continuously removed, separated into the desireddehydrogenated product and hydrogenated hydrocarbons, and thehydrogenated (saturated) hydrocarbons are recycled back to the reactor.

It should be noted here that none of the above discussed reactionsinvolve the complete reaction of all of the reactants to form thedesired product. Rather the reactions are reversible equilibriumreactions wherein the presence of excess hydrogen, or an absence ofhydrogen, or a change in temperature shifts the equilibrium to cause ashift in the ratio of products. However, this shift can be bothaccelerated and enhanced by the use of the fullerene catalysts, inaccordance with the invention.

The following examples will serve to illustrate the process of theinvention.

EXAMPLE I

To illustrate the cleavage (hydrogenolysis) of 1,2-dinaphthyl methane,equal molar parts of 1,2-dinaphthyl methane and dihydrophenanthrene (thehydrogen source) may be contacted with at least about 5 molar % of a C₆₀fullerene catalyst at a temperature of about 300° C. at ambient pressurefor a period of about 2-3 hours. The result will be a mixture ofnaphthalene, 1-methyl naphthalene, and 2-methyl naphthalene (the cleavedproducts) and phenanthrene.

EXAMPLE II

To illustrate the hydrogenation of phenanthrene to dihydrophenanthrene,phenanthrene heated to a temperature of about 300° C. at whichtemperature it is a liquid, was contacted with hydrogen gas at apressure of about 1000 psi and with about 5 molar % of C₆₀ fullerenecatalyst for about an hour, with shaking or stirring, as needed, tofacilitate mass transfer of the hydrogen from the gas phase to theliquid phenanthrene. The result will be the production ofdihydrophenanthrene.

EXAMPLE III

To illustrate the dehydrogenation of dihydrophenanthrene tophenanthrene, dihydrophenanthrene was heated to a temperature of about300° C. at ambient pressure and contacted with about 5 molar % of C₆₀fullerene catalyst for about an hour. The result will be the productionof phenanthrene and the liberation of hydrogen gas.

Thus, the invention provides a new process for processing hydrocarbonswhich eliminates the need for either a solid catalyst or a solidcatalyst support for the dehydrogenation or hydrogenation, includinghydrogenolysis, of hydrocarbons by using one or more soluble fullerenecatalysts to thereby minimize coking reactions and resultant undesirablecoke formation on a solid catalyst or catalyst support.

Having thus described the invention what is claimed is:
 1. A process forhydrogenolysis of one or more substituted aromatic hydrocarbons whichcomprises contacting said substituted aromatic hydrocarbon, in thepresence of hydrogen, with one or more fullerene catalysts to cleave asubstituted moiety from the aromatic ring.
 2. The process of claim 1wherein said one or more fullerene catalysts are soluble to therebyinhibit coke formation, and said process includes the further step offorming a solution containing said one or more soluble fullerenecatalysts.
 3. The process of claim 2 wherein said one or more fullerenecatalysts each has the formula C_(n), where n is an even integer from 50to about
 120. 4. The process of claim 3 wherein said one or more solublefullerene catalysts each has the formula C_(n), where n is an eveninteger from about 60 to about
 90. 5. The process of claim 2 whereinsaid hydrogenolysis reaction is carried out at a temperature rangingfrom about 25° C. to about 500° C. and at a pressure ranging from about100 Torr to about 50,000 Torr.
 6. The process of claim 2 wherein saidsubstituted aromatic hydrocarbon has the formula Ar-M where Ar is aradical of a 6-30 carbon aromatic ring compound, and M is an aliphaticradical selected from the group consisting of X, R, OR, SR, and NRR',where X is a halogen other than fluorine, R is a 1-30 carbon alkylgroup, and R' is hydrogen or a 1-30 carbon alkyl group.
 7. The processof claim 6 wherein Ar is a radical of a 10-30 carbon aromatic ringcompound.
 8. The process of claim 2 which includes the additional stepof separating the reaction products from the reaction.
 9. The process ofclaim 2 wherein said substituted aromatic is a solid dissolved in asolvent which is miscible with said fullerene catalyst solution.
 10. Theprocess of claim 2 wherein said substituted aromatic is a liquid whichis miscible with the solvent in which said one or more fullerenecatalysts are dissolved.
 11. The process of claim 2 wherein saidsubstituted aromatic hydrocarbon is a liquid and said one or morefullerene catalysts are dissolved in said liquid aromatic hydrocarbon.12. A process for hydrogenation of one or more unsaturated hydrocarbonswhich comprises contacting said unsaturated hydrocarbon, in the presenceof hydrogen, with one or more fullerene catalysts to hydrogenate saidunsaturated hydrocarbon.
 13. The process of claim 12 wherein said one ormore fullerene catalysts are soluble to thereby inhibit coke formation,and said process includes the further step of forming a solutioncontaining said one or more soluble fullerene catalysts.
 14. The processof claim 13 wherein said one or more fullerene catalysts each has theformula C_(n), where n is an even integer from 50 to about
 120. 15. Theprocess of claim 14 wherein said one or more fullerene catalysts eachhas the formula C_(n), where n is an even integer from about 60 to about90.
 16. The process of claim 13 wherein said hydrogenation is carriedout at a temperature ranging from about 25° C. to about 500° C. and at apressure ranging from about 100 Torr to about 50,000 Torr.
 17. Theprocess of claim 13 wherein said unsaturated hydrocarbon is a 2-100carbon olefinic hydrocarbon.
 18. The process of claim 13 wherein saidunsaturated hydrocarbon is a 6-30 carbon aromatic hydrocarbon.
 19. Theprocess of claim 13 which includes the additional step of separating thehydrogenated reaction product from the reaction.
 20. The process ofclaim 13 wherein said unsaturated hydrocarbon is a solid dissolved in asolvent which is miscible with a fullerene solution formed from said oneor more soluble fullerene catalysts.
 21. The process of claim 13 whereinsaid unsaturated hydrocarbon is a liquid which is miscible with asolvent in which said one or more soluble fullerene catalysts aredissolved.
 22. The process of claim 13 wherein said unsaturatedhydrocarbon is a liquid and said one or more soluble fullerene catalystsare dissolved in said liquid unsaturated hydrocarbon.
 23. Ahydrogenation process for forming a hydrocarbon product from a differenthydrocarbon starting material which comprises contacting with one ormore fullerene catalysts a hydrocarbon starting material selected fromthe group consisting of an olefinic hydrocarbon, a cyclic hydrocarbon,an aromatic hydrocarbon, and a substituted aromatic hydrocarbon, whilemaintaining said hydrocarbon starting material at a temperature rangingfrom about 25° C. to about 500° C. and at a pressure of at least about 1Torr, to cause said hydrocarbon starting material to react to form saiddifferent hydrocarbon product, with hydrogen present during at least aportion of said reaction.
 24. A hydrogenation process for forming ahydrocarbon product from a different hydrocarbon starting material whichcomprises contacting a hydrocarbon starting material selected from thegroup consisting of an olefinic hydrocarbon, a cyclic hydrocarbon, anaromatic hydrocarbon, and a substituted aromatic hydrocarbon; in thepresence of hydrogen; with one or more fullerene catalysts; to causesaid hydrocarbon starting material to react to form said differenthydrocarbon product, while maintaining said hydrocarbon startingmaterial at a temperature ranging from about 25° C. to about 500° C. andat a pressure of at least about 100 Torr during said reaction.
 25. Thehydrogenation process of claim 24 wherein said hydrocarbon startingmaterial is a substituted aromatic and said hydrogenation comprises ahydrogenolysis reaction.